Circuit breaker with thermal-magnetic trip assembly



Jan; s, 1967 G. E. AUTHIER l 3,296,563

CIRCUIT BREAKER WITH THERMAL-MAGNETIC TRIP ASSEMBLY Original Filed Jan.'

2 Sheets-Sheet l vFIGA 'INSULATION `FIRE FIG.2

Jan. 3, 1967 G. E. GAUTHIER CIRCUIT BREAKER WITH THERMAL-MAGNETIC TRIP ASSEMBLY 2 Sheets-Sheet 2 Original Filed Jan. 7, 1965 INSULATION NVENTR. GG 6007/175@ ,4770 RME United States Patent O 3,296,563 CIRCUIT BREAKER WITH THERMAL-MAGNETIC TRIP ASSEMBLY George E. Gauthier, Plainville, Conn., assignor to General Electric Company, a corporation of New York Continuation of application Ser. No. 423,942, Jan. 7, 1965. This appiication May 2, 1966, Ser. No. 554,616 12 Claims. (Cl. 335-10) This case is a continuation of application Serial Number 423,942, tiled January 7, 1965. The present invention relates to multipole circuit breakers and particularly to multipole circuit breakers having movable contacts operated between open and closed positions by an operating mechanism which includes a trip member releasable to cause automatic opening of the contacts and wherein automatic opening of the contacts may be effected by thermally responsive means or a magnetically operated armature to interrupt the current at a desired value.

In circuit breakers which are adapted to control relatively high values of current such as for instance 600 to 1200 amperes, it is desirable to utilize combined thermal and magnetic tripping devices. In such arrangements there is included a thermal tripping element heated in response to current in the main conductors by means comprising a transformer type of coupling. The same magnetic core which provides coupling of the current in the main conductors to the thermal tripping element may also provide the magnetic flux to attract a magnetic tripping device such as an armature, for instance. In conventional construction and fabrication of such multipole circuit breakers, it was usual to assemble the combined thermal and magnetic tripping device for each pole separately, positioning the assembly in a pole chamber of an insulating casing in proper spatial disposition with respect to the primary conductors and the operating mechanism for automatically opening the contacts to interrupt the flow of current under overload conditions. Frequently such fabrication and assembly techniques involved the use of different designs and configurations of magnetic and thermal tripping units and their associated mechanisms for each different current rating of circuit breakers.

For ease and economy of manufacture, uniformity of construction, and reduction in parts inventory, it is highly desirable that subassemblies for multipole circuit breakers be conceived for manufacture in a common form adaptable to use in a wide range of ampere ratings of circuit breakers.

Accordingly, it is an object of the present invention t provide thermal and magnetic tripping devices of the transformer type in a unitary assembly for use with multipole circuit breakers.

It is another object of the present invention to provide such an assembly having a minimum number of members which are determinative of ampere rating.

Yet another object of the present invention is to provide an assembly of thermal and magnetic tripping units for use in multipole circuit breakers wherein a basic structural support is an insulating member having a plurality of apertures therein for passing primary conductors therethrough in electrical isolation from proximate magnetic core members adjacent each such aperture.

Yet another object of the present invention is to provide a subassembly for multipole circuit breakers including magnetic core members having at least one high reluctance section and having means adapted to be mounted on the assembly for selectively establishing the reluctance of such high reluctance section.

In accordance with the invention in one form, a subassembly for a multipole circuit breaker is provided which comprises a unitaiy insulating member configured to be received and supported in an insulating casing of the ICC circuit breaker and having a plurality of apertures for passing primary current conductors therethrough. A magnetic core member is mounted on the insulating member adjacent each of the apertures and spaced thereabout in electrical isolation from the proximate primary conductor. A secondary winding, preferably in the form of a solid, single-turn, short-circuited copper member is mounted on each core member and supported by the unitary insulating member. Thermally responsive means, usually in the form of a bimetallic strip, is iixedly positioned in thermal contact with each secondary winding and a pair of magnetic pole extensions attached to the unitary insulating member opposite each core member in spaced disposition to deiine an air gap magnetically in parallel with each associated magnetic core. The magnetic core members of the structure may have one or more high reluctance sections and in accordance with the concept of the present invention in one form, means are provided for selectively establishing the reluctance of at least one of the high reluctance sections of each magnetic core, which means may typically take the form of a section of paramagneticmaterial aixed to the unitary insulating member on the opposite side from a magnetic core and adjacent a high reluctance section of the magnetic core.

In accordance with another aspect of the invention, substantially the same subassembly for use in multipole electric circuit breakers may be provided and adapted to include only thermal tripping means for automatic interruption of current under overload conditions. Alternatively, substantially the same form of subassembly may be provided and adapted tov employ only magnetic tripping means to similarly interrupt current in the primary conductors under overload conditions.

Additional objects and aspects of the invention will be pointed out in the following detailed description and illustrated in the accompanying drawings and the scope of the invention will be particularly pointed out in the appended claims.

In the drawings,

FIGURE l is a side elevational, partially cross-sectional view of a multipole circuit breaker embodying the present invention;

FIGURE 2 is a more detailed cross-sectional view of a portion of the multipole circuit breaker of FIGURE l;

FIGURE 3 is a partial view of the subassembly of the present invention as employed in the multipole circuit breakers of FIGURES l and 2;

FIGURE 4 is an exploded perspective view of the discrete parts and members and the manner in which they are combined to form the subassembly of the present invention;

FIGURE 5 is a perspective view of an embodiment of the present invention in its combined and assembled form.

Referring now to FIGURE 1, there is shown at 10 a multipole circuit breaker having an outer insulating casing 11. The illustrated circuit breaker 10 is of the type having a manually operable handle 12 which may be reciprocally positioned in accordance with its on or off condition. The handle 12 is connected through appropriate over center spring loaded linkage 13 to position a pair of movable electrical contacts 14 and 15. The spring loaded linkage mechanism 13 also includes a latch mem` ber 16 adapted to be secured in latched position with a trip linkage shown generally at 17 which may be actuated for automatic interruption of the current flow through the main conductors of the circuit breaker under overload conditions by a trip unit in response to either a thermal tripping device or a magnetic tripping as will be explained more fully hereinafter.

Movable contacts 14 and 15 of the circuit breaker 10 are shown in a position of contact with a pair of main contacts 18 and 19 which are supported on a main conductor 2l). A pivoted arm 21 supports the movable contacts 14 and 15 and is electrically connected to a llexible conductor 22 which in turn is in electrical connection with a conductor strap 23 and a main conductor 24 which passes through an aperture in a trip unit 25 enclosed witha housing comprising two mating molded parts 25a and 25b. The base 25a is the larger of two and serves as a support for parts of the trip mechanism while the part 25b serves as a cover. The trip unit 25 is responsive to the ow of overload currents in the main conductor 24 to release the latch contacts of the circuit breaker and interrupt the flow of overload currents. The circuit breaker is of the multipole type which comprises an insulating casing 11 having a plurality of pole chambers and a plurality of movable contacts in each of the pole chambers. As previously mentioned the movable contacts 14 and 15 of such a single pole chamber may be positioned in the on position of engagement with the stationary electrical contacts 18 and 19 or the handle 12 may be positioned in the off position, disengaging the movable contacts 14 and 15 in each such pole chamber from their associated stationary contacts such as 18 and 19, and interrupting the flow of current therethrough by either manual actuation of the handle 12 or automatic operation in response to a thermally sensitive or magnetic tripping device.

Referring now to FIGURE 2, there is shown in more detail a unit of a typical multipole circuit breaker with the latching member 16, its latched position corresponding -to the on position of the circuit breaker as is illustrated in FIGURE 1. A boss which is part of the trip unit housing cover 25b carries a pivot 36. A trip bar 26 is pivotally supported in the housing base 25a by a pivot pin 27 so as to be engageable with a thermally responsive strip 28 through an adjusting screw 28a. The opposite or lower end of the trip bar 26 carries an armature 3S which is positioned to be engageable by an adjustable stop screw 29 supported on the inner wall of the trip unit housing cover 25b for establishing the desired disposition of the armature 35. A primary conductor 24, cori responding to that shown in FIGURE 1, is shown in FIGURE 2 as passing through an assembly which comprises an insulating member 30 having a plurality of laminated, magnetic core members such as that shown at 31 mounted thereon. The unitary insulating member 30 is configured to be received and supported in the trip unit housing 25 shown in FIGURE 1, and has a plurality of apertures for passing primary conductors such as 24 therethrough which are bolted -to the housing 25. In addition to the plurality of laminated, magnetic core members such as that shown at 31, which are mounted on the insulating member 30, the insulating member supports a secondary winding mounted on each core member.

The secondary winding, as shown at 32, is preferably of the single turn, short-circuited type and may typically comprise a single loop of solid copper. A thermally responsive means 28, which may take the form of a bimetallic strip is fxedly attached to the secondary winding 32. A lirst pair of megntic pole extensions 33 is mounted on the insulating member 30 opposite each magnetic core member and spaced apart to define an air gap which is magnetically in parallel with its associated magnetic core member 32. A second pair of magnetic pole extensions 34 is mounted on the outer portions of the first pair of pole extensions 33. A magnetic armature 35 is supported on the lower portion of the trip bar 26 and includes a portion adapted to extend across the first pair of magnetic pole extensions 33 or the second pair of magnetic pole extensions 34 magnetically in parallel with the magnetic core member 31. The trip bar 26 including the magnetic armature 35 at its lower extremity is biased in a counterclockwise direction by appropriate spring means as shown in its set or latched position. An armature adjusting screw 29 is provided which is threadedly engaged in the cover portion 25b of the trip unit housing.

Current passing through the primary conductor 24 creates a magnetic field which courses through the magnetic core member 31, a portion of such magnetic ilux passing through the magnetic pole extensions 33 and through the auxiliary magnetic pole extensions 34. The armature 35 also provides a part of this latter parallel magnetic tlux path and upon the flow of normal currents, the effect of such magnetic flux is to tend to hold the armature 35 in its shown retracted position against the armature adjusting screw 29. On the occurrence of high overload current conditions, however, the intermediate portion of the auxiliary magnetic poles 34 become magnetically saturated and a pull is created directly between the extremities of the magnetic pole portions 33 and the armature 35. The armature 35 is thus caused to move to the left as viewed in FIGURE 2, displacing the trip bar 26 4to depress the toggle linkage of the trip mechanism 17, allowing the spring loaded latch member 16 to escape from its latched position and rapidly disengaging the movable contacts 14 and 15 from the stationary contacts 18 and 19 which are shown in FIGURE l.

The thermal type of tripping operation is similarly responsive to the How of excessive overload current conditions in the primary conductor 24. The current flowing in the primary cond'uctor 24 creates a magnetic field which passes through the magnetic core member 31 and courses the single turn short-circuited secondary winding 32. Because the secondary winding 32 is short-circuited and a very good electrical conductor such as copper, for instance, very high eddy currents are generated in the secondary winding which quickly heat the metal of the single turn secondary winding 32. The heat is rapidly transmitted to the thermally responsive element 28, such as a bimetallic strip, by reason of thermal conduction due to its direct contact with the secondary winding 32. The thermally responsive element 28 is constructed, arranged and positioned to deect to the right as viewed in FIGURE 2 causing the Calibrating screw 28a to engage the trip bar 26 and to displace it in a clockwise direction, actuating the trip mechanism as previously d'escribed in connection with the magnetically induced actuation provided by the parallel magnetic path through the magnetic armature 35.

FIGURE 3 shows a portion of the multipole circuit breaker of FIGURES 1 and 2 and in particular illustrates a portion of a particular assembly as conceived by the present invention. A unitary, substantially planar insulating member 30 is shown as having an aperture 37 through which a main conductor 24 passes. A magnetic core member is mounted on the insulating member 30 in the manner shown in FIGURE 2 and adjacent each aperture such as that shown at 37 in FIGURE 3. Each such magnetic core member may be of a generally rectangular outside contguration and having an aperture therein which is spaced about the aperture of the insulating member 30 so as to provide electrical isolation of the core member from the primary conductor 24. Each such magnetic core member may have one or more high reluctance sections as will be explained more fully hereinafter.

A secondary winding, preferably in the form of a single continuous loop of copper effectively short circuited in itself, is mounted about each core member in the manner shown in FIGURE 2 and supported on the insulating member 30 by appropriate means such as the threaded screw shown at 38 in FIGURE 3. A thermall)I responsive strip 28 is supported on the secondary winding and includes a Calibrating threaded screw member 28a. A first pair of magnetic pole extensions is attached to the insulating member 34) opposite each magnetic core member and spaced apart as shown at 33a and 33b to define an air gap magnetically in parallel with its associated magnetic core member. An auxiliary pair of magnetic pole extensions 34a and 3417 are similarly affixed and supported on the insulating member 30 to provide an auxiliary air gap magnetically parallel with its assop ciated magnetic core member.

FIGURE 4 shows in `more detail the elements and components of the assembly of the present invention in an exploded perspective view. A unitary substantially pla-nar insulating member shown generally at 40 is configured to be received and supported in an insulating casing of a multipole circuit breaker such as that shown in FIGURE 1 which may typically be a three-phase circuit breaker. The insulating member 40 has a plurality off-apertures 41, 42 and 43 which are dimensioned and positioned to permit the passage of primary conductors therethrough in the manner previously explained in the descriptionsof FIGURES 2 and 3. A magnetic core member such as that shown generally at 44 in FIGURE 4 is mounted on insulating member 40 adjacent each of the apertures 41, 42 and 43. It Will be noted that the magnetic core member 44 may be comprised of two substantially C-shaped sections of laminated paramagnetic material which are arranged and positioned facing each other so as to provide an air gap as shown at 45. The air gap 45 forms a high reluctance section of the magnetic path through the magnetic core member 44 and a similar partial or entire air gap may be provided on the top portion of the magnetic core member such as that shown at 44 forming a second high reluctance section `enclosed within the secondary winding 46. As illustrated in FIGURE 4, the secondary winding 46 comprises a 4single turn, short-circuited continuous loop of highly electrically conductivek materials such as copper. The secondary winding 46 is threaded as shown at 47 to receive an appropriate screw means 4S supporting the secondary winding on the insulating member 40. In the manner previously described in connection with FIGURES 2 a-nd 3, a thermally responsive member 49 is affixed in thermal Contact on the secondary winding 46. A first pair of magnetic pole extensions 50a and 50!) configured and adapted to be positioned on the insulating member 40 opposite an associated core member 44 provides an air gap defining a parallel magnetic path. A second pair of magnetic pole extensions 51a and 5119 is positioned adjacent to the first pair of magnetic pole extensions forming a secondary parallel magnetic path with the magnetic core member 44. The assembly of the magnetic core member 44 and the two pairs of magnetic pole extensions together with the insulating member 40 may be joined and supported commonly by appropriate means such as the elongatedrivets shown at 52, 53, 54 and 55. An additional member 56 may be supported on the insulating member 40 in proximity to the air gap 45 and such mem-- ber may preferably be of a paramagnetic material so as tothereby selectively predetermine the reluctance of the high reluctance section of the magnetic core 44 formed by the air gap 45. The member 56 may be of various sizes and materials as desirable to afford varying degrees of. modifying the reluctance of the high reluctance section of the magnetic core 40 and is appropriately aixed tothe insulating member 40 by screw means such as shown at 57 and 5S.

The complete subassembly as conceived by the present invention is shown in FIGURE and comprises a unitary substantially planar insulating member 30 which is configured and dimensioned to be supported a-nd enclosed within the base and cover of the trip unit housing of a three pole circuit breaker. Such support may be effected through appropriate screw means 58 as shown in FIGURE 4 and adapted to pass through the insulating member 30, securing the assembly of FIGURE 5 to block portion 59 of the base of the trip unit housing.

Referring now to FIGURE 5, the insulating member 30 is provided with a plurality of apertures 41, 42 and 43 adapted to pass primary current conductors of the circuit breaker therethrough and preferably being so dimensioned 6 44, 65 and 66 are mounted on the insulating member 3() adjacent each of the apertures 41, 42 and 43 respectively. A secondary winding adapted to be energized by each respecitve magnetic core member is mounted on its associated core member such as the secondary windings shown at 46, 68 and 69 mounted on core members 44, 65 and 66 respectively. As was previously noted, such secondary windings may preferably be comprised of a single loop of continuous copper conductor constituting a single-turn, short-circuited secondary winding. The secondary windings 46, 68 and 69 are supported by appropriate means such as the screw members 70, '71 and 72 which pass .through the insulating member 30 and are threaded into the secondary windings 46, 68 and 69 respectively. First and second pairs of magnetic pole extensions as shown at 50a and 50]), and 51a and 51h respectively in FIG- URE 5 are associated with each magnetic core member in the preferred embodiment of the present invention and supported on the insulating member 30 by appropriate means such as t-he elongated rivets described previously in connection with FIGURE 4. Pairs of magnetic pole extensions substantially identical to those shown in juxtaposition on core 44 are similarly positioned with respect to magnetic cores 65 and 66. The pairs of magnetic pole extensions each define an air gap which is magnetically in parallel with the associated magnetic path defined by the proximate magnetic core. An additional magnetic path for each of the core members 44, 65 and 66 is provided by the members 56, 76 and 77 as supported on the insulating member 30 and positioned adjacent the air gaps which constitute high reluctance sections of the respective magnetic core members 44, 65 and 66. This latter arrangement provides a means by which the high reluctance section of each core may be modified and changed or fixed in a predetermined degree of magnetic reluctance.

As will be appreciated by those knowledgeable in the art, the present invention provides a multipole circuit breaker subassembly which, because of its unitary construction is rigid and structurally stronger than comparable separate units are previously had been installed in each pole chamber of multipole circuit breakers. At the same time the present invention provides a basic assembly which can be employed with circuit breakers which typically may vary from ampere ratings of 600 amperes to 1200 amperes. Commercially such multipole circuit breakers of relatively higher current capacities may be available in ratings of 600 amperes, 700 amperes, 800 amperes,.

1000 amperes and 1200 amperes and the assembly of the present invention is readily adapatable to all these ratings of circuit breakers, though not limited to these ratings.

Additionally the assembly of the present invention provides in its concept that either the thermal or the magnetic trip units may be excluded from the assembly to provide for exclusive thermal or magnetic automatic trip actuation. In some electrical installations it has been found desirable to employ a circuit breaker type of unit as a manually or remotely controllable switch. T-he concept of the present invention is such that it is readily adaptable to employing a circuit breaker type of unit to such a function by excluding from its assembly both the thermal and the magnetic trip devices so that the circuit breaker type of assembly functionally is the equivalent of an electrical switch of high current capacity which may be readily adapted to remote control.

Additional advantages and desirable features are to be realized in that fewer parts of circuit breakers constructed and assembled in accordance with the concept of the present invention are determinative of the ampere rating of the complete circuit breaker. Moreover, inherent in the concept of the present invention is the adaptability to methods of manufacture of multipole circuit breakers wherein the base, cover, latching system and current carrying parts of the trip unit are common to a broad range of ratings of multipole circuit breakers and can therefore be Iproduced in economical quantities. In this method of manufacture the thermal and magnetic subassemblies of the present invention are positioned with the latching subassembly between the trip unit base and cover, the primary conductors are bolted to the trip unit for insertion of the trip unit into the main housing of a multipole circuit breaker having any one of a broad range of thermal and/ or magnetic trip current ratings.

While the invention has been shown in one specific preferred embodiment it will be readily apparent that many modifications thereof may be made without departing from the spirit of the invention. It is therefore intended bythe appended claims to cover all such modications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker trip unit for a multipole electric circuit breaker comprising an insulating casing, a generally planar unitary insulating member supported in said insulating casing and having a plurality of apertures for passing primary current conductors therethrough, a generally rectangular magnetic core member mounted on said insulating member adjacent each of said apertures, each of said core members having an aperture therein in alignment with said corresponding aperture of` said insulating member, latch means carried by said trip unit for restraining said circuit breaker in closed circuit condition, an armature movably supported on said trip unit casing adjacent each of said core members for move-- ment toward and away from the corresponding one of said magnetic core members, and means interconnecting each of said armature members and said latch member for causing releasing movement of said latch upon attraction of any of said armature members to its corresponding core member.

2. An electric circuit breaker trip unit comprising an insulating casing, a generally planar support member of insulating material, means mounting said support member in said insulating casing, said support member having at least two apertures therein for receiving primary conductors therethrough, a generally rectangular magnetic core member supported on said support member adjacent each of said apertures, each of said core members having an aperture therethrough in substantial alignment with corresponding aperture of said support member, said aperture of said core member being larger than said aperture of said support member, whereby said primary conductors are maintained in spaced relation to said core members, common tripping means supported on said insulating casing, a movable armature member movably supported on said insulating casing adjacent each of said magnetic core members, means interconnecting each of said armature members to said common trip member whereby to cause actuation of said common trip member upon movement of at least one of said armatures toward said magnetic core member.

3. A subassembly for a multipole circuit breaker comprising a unitary insulating member congured to be received andv supported in an insulating casing and having a plurality of apertures for passing primary current conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from :said primary conductors, a secondary winding mounted Ion each of said core member and supported by said inysulating member, and a thermally responsive means positioned in thermal contact with each of said secondary windings.

4. A subassembly for a multipole circuit breaker comprising a substantially planar unitary insulating member conligured to be received and supported in an insulating casing and having a plurality of apertures for passing primary current conductors therethrough, a magnetic core member mountt Q1)` Said ,insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from said primary conductors, each said magnetic core member having at least one high reluctance section, a secondary winding adapted to be energized by each of said magnetic core members and surrounding at least a portion of a high reluctance section, and a thermally responsive means supported on each of said secondary windings and in thermal contact therewith.

5. A subassembly for a multipole circuit breaker comprising a substantially planar unitary insulating member configured to be received and supported in an insulating casing, said insulating member having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from said primary conductors, each said magnetic core member having at least one high reluctance section, and a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member and spaced apart to define an air gap magnetically in parallel with ahigh reluctance section of each said magnetic core.

6. A subassembly for a multipole circuit breaker comprising a substantially planar unitary insulating member configured to be received and supported in an insulating casing, said insulating member having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from said primary conductors, each said magnetic core member having at least one high reluctance section, a secondary winding adapted to be energized by each said magnetic core member and surrounding at least a portion of a high reluctance section, a thermally responsive means supported on each said secondary winding and in thermal Contact therewith, and a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member and spaced apart to dene an air gap magnetically in parallel with a high reluctance section of each said magnetic core'. y.'

7. A subassembly for .a multipole circuit breaker comprising a substantially planar unitary insulating member configured to be received and supported in an insulating casing and having a plurality of apertures for passing primary current conductors therethrough, a magneticcore member mounted on said insulating member adjacent each of said apertures, each said magnetic core member having two high reluctance sections, a secondary winding adapted to be energized by each said magnetic core member and surrounding at least a portion of one of said high reluctance sections, a thermally responsive means supported on each secondary winding and in thermal contact therewith, and means for selectively establishing the reluctance of at least one of said high reluctance sections of each said magnetic core.

8. A subassembly for a multipole circuit breaker comprising a substantially planar unitary insulating member contigured to be received and supported in an insulating casing and having a plurality of apertures for passing primary current conductors therethrough, a magnetic core member mounted 0n said insulating member adjacent each of said apertures and spaced thereabout for electrical insulation from said primary conductors, a `single-turn, short-circuited secondary winding mounted around each said core member and supported by said insulating' member, and a bimetallic strip mounted on each said secondary winding.

9. A trip unit assembly for a multipole circuit breaker comprising an insulating base and cover, a latching assembly adapted to be received and supported by said insulating base and cover, a substantialiy planar unitary insulating member configured to be received and supported within said insulating base and cover and having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from said primary conductors, a secondary winding mounted on each said core member in electrical insulation therefrom and supported by said insulating member, a bimetallic strip supported in thermal contact with said secondary winding, and a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member and spaced apart to dene an air gap magnetically in parallel with a proximate magnetic core.

10. A trip unit assembly for a multipole circuit breaker comprising an insulating base and cover, a latching assembly adapted to be received and supported by said insulating base and cover, a substantially planar insulating member configured to be received and supported within said insulating base and cover and having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout for electrical isolation from said primary conductors, each said magnetic core member having two high reluctance sections, a single continuous loop of copper mounted around each said core member in electrical insulation therefrom and surrounding at least a portion of one of said high reluctance sections, said copper loop being supported by said insulating member, a bimetallic strip xedly attached to each said copper loop, a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member and spaced apart to dene an air gap magnetically in parallel with a high reluctance section of a proximate core, and means adapted to be mounted on said assembly for selectively establishing the reluctance of at least one of said high reluctance sections of each said magnetic core.

11. A multipole electric circuit breaker comprising an insulating casing having a plurality of pole chambers therein, a pair of movable contacts in each of said pole chambers, operating mechanism in at least one of said pole chambers for operating said movable contacts between open and closed positions, said operating mechanism including a trip member releasable to cause automatic opening of said contacts, at least one magnetic armature pivotally supported for movement to engage said trip member, a substantially planar insulating member configured to be received and supported in said insulating casing and having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout in electrical isolation from said primary conductors, a secondary winding mounted on each said core member and supported by said insulating member, a thermally responsive means supported in thermal contact with each said secondary winding and positioned to actuate said trip member, and a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member defining an air gap magnetically in parallel with a proximate magnetic core and positioned to actuate said pivotally supported magnetic armature.

12. A multipole electric circuit breaker comprising an insulating casing having a plurality of pole chambers therein, a pair of movable contacts in each of said pole chambers, operating mechanism in at least one of said pole chambers for operating said movable contacts between open and closed positions, said operating mechanism including a trip member releasable to cause automatic opening of said contacts, a magnetic armature pivotally supported in each pole chamber for movement to engage said trip member, a substantially planar insulating member configured to be received and supported in said insulating casing and having a plurality of apertures for passing primary conductors therethrough, a magnetic core member mounted on said insulating member adjacent each of said apertures and spaced thereabout in electrical isolation from said primary conductors, each said magnetic core having at least one high reluctance section, a singleturn, short-circuited secondary winding mounted on each said core member and supported by said insulating member, a bimetallic strip iixedly supported on said secondary winding in thermal contact therewith and positioned to actuate said trip member, and a pair of magnetic pole extensions attached to said insulating member opposite each magnetic core member dening an air gap magnetically in parallel with a high reluctance section of a proximate magnetic core and positioned to actuate said pivotally supported magnetic armatures.

No references cited.

BERNARD A. GILHEANY, Primary Examiner.

R. N. ENVALL, Assistant Examiner. 

1. AN ELECTRIC CIRCUIT BREAKER TRIP UNIT FOR A MULTIPOLE ELECTRIC CIRCUIT BREAKER COMPRISING AN INSULATING CASING, A GENERALLY PLANAR UNITARY INSULATING MEMBER SUPPORTED IN SAID INSULATING CASING AND HAVING A PLURALITY OF APERTURES FOR PASSING PRIMARY CURRENT CONDUCTORS THERETHROUGH, A GENERALLY RECTANGULAR MAGNETIC CORE MEMBER MOUNTED ON SAID INSULATING MEMBER ADJACENT EACH OF SAID APERTURES, EACH OF SAID CORE MEMBERS HAVING AN APERTURE THEREIN IN ALIGNMENT WITH SAID CORRESPONDING APERTURE OF SAID INSULATING MEMBER, LATCH MEANS CARRIED BY SAID TRIP UNIT FOR RESTRAINING SAID CIRCUIT BREAKER IN CLOSED CIRCUIT CONDITION, AN ARMATURE MOVABLY SUPPORTED ON SAID TRIP UNIT CASING ADJACENT EACH OF SAID CORE MEMBERS FOR MOVEMENT TOWARD AND AWAY FROM THE CORRESPONDING ONE OF 